Early 101a networks

[Kenton K]

I had a wall 653 I was cleaning up to sell and I realized the nework looked strange. It's a 101a (I think) that's dated I 1937. Does anyone have any info on these early networks? I've never seen one before.

Kk

[Ktownphoneco]

It's an early version of the 101-A induction coil.     The marking "101-A", although sometimes difficult to see,  should be located on the fiber coil end cap on the opposite side to the date stamp.
If memory serves me, they first appeared in Western's 1935 Telephone catalog.     I would imagine most of the factory assembly on these coils was done by hand.     The iron core laminates are held together with machine screws.   
I believe it was Unbeldi who mentioned that the switch over to rivets occurred sometime in 1938. 

Jeff Lamb

[TelePlay]

I had a wall 653 I was cleaning up to sell and I realized the nework looked strange.

Well, that ends that "for sale" project, having an original coil, that is. Can you post a picture of that 653?

[Kenton K]

Cool! Its also got a III 1936 4H dial too. (I think, date is obscured). But man, I really should sell it tho. I have a second 653 that is virtually the same.

The last photo is both of my 653s.

KK

[unbeldi]

This "early" version of the 101A actually existed from ca. 1930 on, when it was first mentioned in the Bell history, so by this time (1937) it was already 6 or 7 years old.  It can be found in all the prototypes of the 302 starting in 1932 and the corresponding wall phone, but was announced for use in subsets at the time. However, we don't seem to find any 684s of the time with them.  In technical detail it was first documented in the BSPs in June 1931. It was only called the No. 101 in those times, and gained the A suffix in ca. 1935.

http://www.classicrotaryphones.com/forum/index.php?topic=11422.msg129655#msg129655

[Babybearjs]

would a newer 101A network fit? if the mountings the same and there is transmission problems maybe an upgrade would help... if not, then leave it be.... have you tested the phones on a regular land line for performance?  nice phones.... I have a AE #21 hall phone that I restored and works... it my keeper and the oldest phone in my collection. I'd keep those and get them mounted on some nice back boards.... what eye catchers!

[Jack Ryan]

would a newer 101A network fit? if the mountings the same and there is transmission problems maybe an upgrade would help

Is there any electrical difference between a 101 and a 101A induction coil? The winding resistances are the same suggesting there is no difference.

Also, these are induction coils - not "networks". Network, in the Western Electric sense, is a combination of components that forms the bulk of a telephone circuit - such as the 425 as used in 500 sets.

Jack

[Kenton K]

Good clarification. Network =\= induction coil. I have tested the phone and it works well. It uses the ha1 and f1 elements so it is basically 302 circuitry. I looked carefully at the induction coil and as Jeff said, the laminated core is bolted together. That's is a lot of work! A seems lot of things  switched from using screws to rivets. Network cores, type 7 dial assemblies, 500 feet, ha1 driver thingy, but odly not 302 feet. Those were switched from rivets to screws.

Kenton

[unbeldi]

Small correction to my account of the history.   The designation 101A, i.e.  with the suffix, was already in use in 1933*, but the 1935 catalog still describes it simply as 101 in the induction coil entry, but as 101A in a parts picture.

*BSP C31.401 i1 3311 Induction Coils;Description and Use

Is there any electrical difference between a 101 and a 101A induction coil? The winding resistances are the same suggesting there is no difference.

Also, these are induction coils - not "networks". Network, in the Western Electric sense, is a combination of components that forms the bulk of a telephone circuit - such as the 425 as used in 500 sets.

Jack

Do you have a 101 (no suffix) induction coil that you measured ?

My guess is that they would be electrically very similar, if not identical.  The 302-type circuit was firmly established before 1932, even the color coding of all wires, IIRC.

Perhaps the change was that a better material was used for the core lamellae. I seem to recall that some advances were made in that area in the 1930s.

It is true that WECo had the habit of using the term 'network' for the later, potted multi-component assemblies. By electronic design conventions a network is typically a multi-component arrangement of inductances, resistances, and capacitances, perhaps indeed too complex for use for an induction coil even though the windings of the anti-sidetone induction coil are actually a network—internally the three windings are wired in series.  Many sidetone induction coils could not be called a network, since the two windings are often not connected, although some are.

[Jack Ryan]

Do you have a 101 (no suffix) induction coil that you measured ?

No, I just looked in some catalogues for the specified winding resistances. If WE/BELL did not always label the 101A with the A I think that is more evidence of the electrical equivalence of the two induction coils.

Perhaps the change was that a better material was used for the core lamellae. I seem to recall that some advances were made in that area in the 1930s.

I suspect that if core material changes gave a significant improvement in magnetic performance there would be some change to the electrical proprieties of the IC to take advantage of it. It is hard to see from an armchair many years later but the changes look to be related to manufacturing efficiencies.

It is true that WECo had the habit of using the term 'network' for the later, potted multi-component assemblies.

The first papers in BSTJ describing the 500 development used the term "network" and as far as I can see, it has been used ever since. My conclusion is that "network" is the official term rather than one that WE had a habit of using.

By electronic design conventions a network is typically a multi-component arrangement of inductances, resistances, and capacitances, perhaps indeed too complex for use for an induction coil even though the windings of the anti-sidetone induction coil are actually a network—internally the three windings are wired in series.  Many sidetone induction coils could not be called a network, since the two windings are often not connected, although some are.

I know the general definition of "network" but I don't think that is the point; WE chose to call their combination of components a "network". It probably should be Network (proper noun).

As a matter of interest, NE's T9 catalogue has a section for induction coils where the 101A and similar are listed but not the 425 and similar networks. Elsewhere the 425s are listed as components of various telephones and are referred to as "networks".

Jack

[Kenton K]

Because I have two, and I have limited space, I decided to sell it the phone. I posted it on ebay if anyone is curious. The extra room and $$$ I can spend on a gray 500!

http://www.ebay.com/itm/-/122043983345

Thanks-Ken